JPH0775369A - Method and apparatus for controlling phase angle of brushless motor - Google Patents

Abstract

PURPOSE:To enable low-speed range to high-speed range at a high efficiency by controlling the phase of an excitation signal to a motor on the basis of two kinds of pulse signals. CONSTITUTION:A timing signal generator 10 issues pulse signal FG with a cycle of an electric angle 120 deg. latches it into counters 16, 18 of a phase angle sensor division 14, and pulse signal CP with a cycle of an electric angle 20 deg. in response to a pulse signal. A duty directive division directs the duty of an excitation signal of each phase to stator coils 26U, 26V, 26W of a motor according to speed deviation DELTAv. A signal to direct a duty from the duty directive division 21 is given to a duty signal generator 22. The duty signal generator 22 issues duty signals, that is, three-phase excitation signals according to directive values from the duty directive division 21 on the basis of counts of the counters 16,18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor phase angle control method and apparatus, and more particularly to a brushless motor phase angle control method and apparatus capable of driving a brushless motor from a low speed region to a high speed region with high efficiency. .

[0002]

2. Description of the Related Art Conventionally, as a control method of a brushless motor, there is a method of increasing the duty ratio and / or the lead angle of an excitation signal to the brushless motor as the rotation speed of the motor increases. It is shown in the publication.

In this case, a synchronizing signal (Hall signal) synchronized with the rotation phase of the rotor of the motor is generated, and the duty ratio and / or the lead angle are directly different from the synchronizing signal.
One duty signal (lead angle signal) is generated, and these two signals are switched as the motor rotation speed increases.

[0004]

In the prior art described in the above-mentioned Japanese Patent Laid-Open Publication No. Hei 10 (1999) -264, since the duty ratio and / or the lead angle are switched in two stages, it is possible to drive the brushless motor with high efficiency from the low speed region to the high speed region. Was insufficient. Further, although there is a description that the duty ratio and / or the lead angle may be switched in three or more steps, a specific configuration is not shown, and as in the embodiment described in the above-mentioned Japanese Patent Laid-Open No. Hei. In order to create the duty signal (lead angle signal), it is necessary to provide more than one Hall sensor corresponding to the created duty signal (lead angle signal), which complicates the configuration and complicates the assembly. there were.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a brushless motor phase angle control method and device capable of driving a brushless motor from a low speed region to a high speed region with high efficiency.

Another object of the present invention is to provide a brushless motor phase angle control device capable of driving a brushless motor from a low speed region to a high speed region with high efficiency by a simple structure.

[0007]

According to the present invention, a first pulse signal generated in synchronization with a predetermined phase angle position of a rotor of a brushless motor and a second pulse signal generated each time the rotor rotates by a predetermined angle. Of the excitation signal to the motor so that the duty ratio and / or the lead angle increases as the deviation between the motor speed setting value and the motor speed detection value decreases based on these pulse signals. It is designed to control the phase.

[0008]

In the present invention, two kinds of pulse signals are generated, that is, a first pulse signal generated in synchronization with a predetermined phase angle position of the rotor of the brushless motor and a second pulse signal generated every time the rotor rotates by a predetermined angle. Pulse signals are prepared and the phase of the excitation signal to the motor is controlled based on these pulse signals, the duty and lead angle of the excitation signal are
Alternatively, the control can be performed in units of angles corresponding to the cycle of the second pulse signal. Therefore, the lead angle and the duty can be electrically controlled arbitrarily in an angle unit corresponding to the cycle of the first or second pulse signal without mechanically controlling the lead angle. Therefore, when it is desired to finely control the duty or the lead angle of the excitation signal, the rotation angle interval at which the second pulse signal is generated may be set short.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a brushless motor phase angle control method and apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a first embodiment of the present invention,
FIG. 4 is a timing chart showing signal waveforms in the respective parts of FIG. In FIG. 1, a magnetic pole position detector of the rotor, for example, three Hall sensors 6a to 6c is provided on the inner periphery of the stator facing the rotor of the brushless motor 2, and three magnetic pole pieces are provided on the outer periphery of the rotor. .

The Hall sensors 6a to 6c are provided around the rotor at intervals of, for example, 30 degrees along the rotation direction as shown in FIG. Although an eight-pole motor is used in this embodiment, it can be applied to a brushless motor having another number of poles. The Hall sensors 6a to 6c output pulses in response to the magnetic flux from the pole pieces, that is, in response to a predetermined phase angle position of the rotor, the pulse signals (Hall signals) Ha, Hb, As shown in FIGS. 4A to 4C, Hc has a duty ratio of 1/2 and a phase difference of 120 degrees from each other. The pulse signal from the hall sensor is input to the timing signal generator 10.

The encoder 4 rotates in synchronization with the rotor of the motor. For example, 72 slots may be concentrically arranged at equal intervals as shown in FIG. Light from a light source (not shown) is input to the photodetector 8 through the slot of the encoder 4, and the photodetector outputs a pulse signal Op ((d) in FIG. 4) every time the rotor rotates by an electrical angle of 20 degrees. And supplies the timing signal generator 10. here,
The Hall sensors 6a to 6c and the slots of the encoder 4 are arranged in advance so as to have a positional relationship such that the pulses ~ Hc and Op are synchronized with each other as shown in (a) to (d) of FIG.

The timing signal generator 10 generates a pulse signal FG with one electrical cycle of 120 degrees as shown in FIG. 4E in response to the rising and falling of the Hall signals Ha, Hb and Hc. Counter 1 of phase angle detector 14
6 and 18, and in response to the pulse signal Op, the pulse signal CP having an electrical angle of 20 degrees in one cycle is input to the counter 18 as shown in (f) of FIG. Further, the timing signal generator 10 inputs the pulse signal FG or CP to the speed detector 12, the speed detector detects the motor speed based on the input pulse signal, and inputs the speed detection value vd to the speed comparator 20. . The speed comparator 20 compares the input speed set value (target speed) vs. the detected speed value vd, and gives the deviation Δv to the duty instruction section 21.

The duty instructing section 21 is provided with a stator coil 26U, 26V, 26W of the motor according to the speed deviation Δv.
To indicate the duty (energization angle) of the excitation signal of each phase. For example, if Δv> V1, 120 degree duty, if V1 ≧ Δv> V2, 140 degree duty, V
If 2 ≧ Δv> V3, 160 degree duty, V3 ≧ Δv
Then, the duty of 180 degrees (that is, the duty ratio 1 /
Instruct 2) respectively. Here, each speed V1,
The relationship between V2 and V3 is V1>V2> V3. Therefore,
For example, when the speed set value vs exceeds V1, the duty instruction unit 21 instructs, for example, 120 degrees (that is, the duty ratio 1/3) as the duty at the time of starting, and the speed of the motor sequentially increases, that is, the speed detection value increases. The duty instruction value is increased from 120 degrees to, for example, 140 degrees and 160 degrees, and when the speed deviation Δv becomes V3 or less, 180 degrees is instructed as the duty. In the present embodiment, the duty is divided into four stages for instructing, but the present invention can be applied to the case of dividing into a plurality of other stages.

A signal for instructing the duty from the duty instructing section 21 is given to the duty signal generator 22. The duty signal generator 22 generates a duty signal according to the duty instruction value from the duty instruction unit 21, that is, a three-phase excitation signal based on the count values of the counters 16 and 18.

The operation of the counters 16 and 18 of the phase angle detector 14 will be described below. The counter 16 is a pulse signal FG
, For example, in response to the rising edge of the Hall signal Ha, and is reset in response to the rising edge of the Hall signal Ha, and then sequentially counting in response to the rising edge of the pulse signal FG, every rising edge of the third pulse signal FG. Are reset to ((g) in FIG. 4). On the other hand, the counter 18
Is reset at each rising edge of the pulse signal FG, and counts in response to the rising edge of the pulse signal CP ((h) of FIG. 4). The count values of these counters 16 and 18 are given to the duty signal generator 22.

The duty signal generator 22 outputs the duty instruction value from the duty instruction section 21 and the counter 16, 1.
A duty signal is generated as follows according to the count value of 8. In the present embodiment, the phase angle (lead angle) is also advanced by 20 degrees in terms of electrical angle each time the duty instruction value increases by 20 degrees. That is, when the duty instruction value is 120 degrees (duty ratio 1/3), the U-phase excitation signal is raised in response to the reset of the counter 16 and is lowered when the count value of the counter 16 becomes 1. ((I) in FIG. 4). Similarly, the V-phase excitation signal is raised when the count value of the counter 16 becomes 1 and is lowered when the count value becomes 2 ((j) in FIG. 4), and the W-phase excitation signal is generated. Indicates that the count value of the counter 16 is 2
When the count value becomes 3, it is started and when the count value becomes 3, it is started ((k) in FIG. 4). When the duty is 140 degrees (duty ratio 7/18), the U-phase excitation signal is output when the count value of the counter 16 is 2.
Is raised in response to a count value of 5, and is lowered when the count value of the counter 16 becomes 1 ((l) in FIG. 4). Similarly, the V-phase excitation signal is 1
When the count value of 6 is 0, it is started when the count value of the counter 18 becomes 5, and it is lowered when the count value of the counter 16 becomes 2 ((m) in FIG. 4), and the W phase The excitation signal of is raised when the count value of the counter 16 reaches 1 and the count value of the counter 18 reaches 5, and
When the count value of 0 becomes 0 (reset), it is turned off ((n) in FIG. 4). As described above, the U, V, and W phases when the duty instruction value is 120 degrees, 140 degrees, 160 degrees, and 180 degrees (duty ratios are 1/3, 7/18, 4/9, and 1/2), respectively. The relationship between the rise and fall of the excitation signal and the count values of the counters 16 and 18 is shown in the table below.

[Table 1] The duty instruction value is 180 degrees (duty ratio 1 /
Waveform diagrams of the U, V, and W phase excitation signals at the time of 2) are as shown in (o), (p), and (q) of FIG. Therefore, 1/2
This means that the phase angle of the excitation signal of duty is advanced by 60 degrees with respect to the excitation signal of 1/3 duty. The U, V, and W phase excitation signals generated in this manner are transmitted to the amplifier 24.
Is supplied to the stator coils 26U, 26V, 26W via the motor to drive the motor 2. The phase angle detector 14, the duty indicator 21, and the duty signal generator 22 constitute a duty signal generator 30.

Next, the relationship among the rotation speed (rpm), torque (kg.cm) and efficiency (%) of the motor 2 in the excitation signal of each duty will be described with reference to FIGS. 5 to 8. Figure 5
FIG. 4 is a characteristic diagram showing the relationship between the motor rotation speed, torque, and efficiency when an excitation signal with a duty ratio of 1/3 is used.
FIG. 6 is a characteristic diagram when the excitation signals with the duty ratios of 1/3 and 1/2 are switched and used. In this case, when the motor speed is equal to or lower than va, it is driven with an excitation signal with a duty of 1/3, and when the speed is equal to or higher than va, it is driven with an excitation signal with a duty of 1/2, and the maximum rotation speed is increased as compared with FIG. , The efficiency at high speed increases. FIG. 7 shows a duty ratio of 1/3.
6 is a characteristic diagram when the excitation signal of is used by advancing the phase angle as the speed increases, that is, when the phase angle is advanced in the state of FIG. 5, the maximum rotation speed is slightly increased compared to FIG. The peak moves to the high torque side, and the drop in efficiency on the high torque side is gradual. FIG. 8 is a characteristic diagram when the excitation signals with duty ratios of 1/3 and 1/2 are switched and used with increasing speed, and the phase angle is advanced with increasing speed at each duty, that is, in the state of FIG. This is a signal obtained by advancing the phase angle of a 1/2 excitation signal at high speed. In this case, the maximum rotation speed is further increased, the efficiency peak is moved to the higher torque side, and the drop in the efficiency on the high torque side is more gradual than in FIG. 7. In the figure, the case where the phase angle is advanced when the duty is 120 degrees and 180 degrees has been described, but the same effect can be obtained by advancing the phase angle as the speed increases at other duty.

From the above results, by increasing the duty ratio and advancing the phase angle (lead angle) as the motor speed increases, the maximum rotation speed increases and the efficiency peak moves to the high torque side. It was found that it is possible to reduce the drop in efficiency on the high torque side. Therefore, the duty is set to 1 as the motor speed increases as in this embodiment.
By increasing the phase angle by 20 degrees from 20 degrees to 180 degrees and by advancing the phase angle by 20 degrees, the motor can be driven with high efficiency at all times to smoothly increase the motor speed and further increase the maximum rotation speed. .

In this embodiment, when the speed deviation Δv becomes V3 or less, the duty is set to 180 degrees and the lead angle is set to 60 degrees. However, when the motor speed further increases (the speed deviation further decreases), the lead is read. It may be designed to maintain or decrease the duty as the angle is further advanced (increased). For example, the speed deviation Δv is V3 ≧ Δv> V
When 4 (V3> V4), the duty is 180 degrees and the lead angle is 60 degrees, and when the speed deviation Δv is V4 or less, the lead angle is increased while maintaining the duty at 180 degrees, for example, even if it is increased to 80 degrees. Good ((r), (s) in Figure 4)
(T)). Further, when the speed deviation Δv becomes V4 or less, the duty may be set to less than 180 degrees, for example, 160 degrees, and the lead angle may be increased, for example, to 80 degrees. Further, the reduction of the duty and the lead angle when the speed deviation Δv is V3 or less may be controlled in two or more steps. By doing so, it is possible to further reduce the waste of current at high speed.

In this embodiment, the duty of the duty signal (excitation signal) is increased by 20 degrees.
For example, it may be increased by 10 degrees. In that case, for example, if the counter 18 is made to count in response to the rising and falling of the pulse signal CP, the count value of the counter 18 increases in accordance with the rotation of the rotor of the motor every 10 degrees of the electrical angle. Can be increased every 10 degrees. Similarly, the phase angle of each duty signal can be advanced every 10 degrees.
Further, by adjusting the interval between the Hall sensors 6a to 6c and the interval between the slots of the encoder 4, the pulse signal FG,
By changing the CP generation cycle, the duty change angle and the phase angle change angle of the duty signal can be freely set.

Next, a second embodiment will be described. In the above embodiment, until the speed detection value vd reaches the speed setting value vs,
The duty is gradually increased and the lead angle is increased, and when the duty reaches 180 degrees, the duty is maintained at 180 degrees or gradually decreased and the lead angle is further increased. Is set to a fixed value, and the most efficient duty and lead angle duty signals are used in accordance with the speed setting value. For example, when a predetermined low speed v1 is instructed as the speed setting value, the duty is set to 120 degrees, and the lead angle is gradually advanced (for example, to 60 degrees) until the motor speed reaches the setting value v1. High speed v
When 2 is designated, the duty and the lead angle are increased as in the above embodiment, and finally the duty is fixed at 180 degrees and the lead angle is fixed at 60 degrees, for example. By doing so, as is apparent from FIGS. 7 and 8, the motor can be controlled most efficiently at each predetermined speed.

FIG. 9 is a block diagram showing a configuration example of the second embodiment. In the figure, those having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, a switch 28 is provided in front of the speed comparator 20 of the first embodiment shown in FIG.
When the speed set value v1 is instructed, the switch 28 is turned on to the terminal 28a side, and when the speed set value v2 is instructed, the switch 28 is turned on to the terminal 28b side, and the output of the switch 28 is given to the duty instruction section 21. It is what has been. When the speed setting value v2 is instructed by the duty instruction section 21,
The duty is fixed to 120 degrees and the lead angle is increased as the speed deviation Δv decreases. Further, when the speed setting value v1 is instructed, the duty instructing unit 21 first sets the duty to 120 degrees and the lead angle to 0 degrees, and then the speed deviation Δ.
As v decreases, the duty gradually increases and the lead angle gradually increases.
Fix the lead angle at 0 degrees and 60 degrees.

If a large torque is required even if the speed setting value is the low speed v1, the duty may be set to, for example, 180 degrees. The duty according to the speed setting value may be a duty other than 120 degrees and 180 degrees.

Although the pulse signals FG and CP are generated by using the Hall sensor and the encoder in each of the above embodiments, both signals may be generated only by the encoder. The encoder in this case is as shown in FIG.
In addition to the 72 slots of the encoder shown in FIG. 3, 24 slots for generating the pulse signal FG may be provided concentrically at equal intervals.

[0025]

As described above, according to the present invention, two kinds of pulse signals, that is, the first pulse signal generated in synchronization with a predetermined phase angle position of the rotor of the brushless motor and the rotor rotate by a predetermined angle. Since the second pulse signal generated for each time is prepared and the phase of the excitation signal to the motor is controlled based on these pulse signals, the duty and lead angle of the excitation signal are set to those of the first or second pulse signal. It becomes possible to control in units of angles corresponding to the cycle. Therefore, the lead angle and the duty can be electrically controlled arbitrarily in an angle unit corresponding to the cycle of the first or second pulse signal without mechanically controlling the lead angle. Therefore, when it is desired to finely control the duty or the lead angle of the excitation signal, the rotation angle interval at which the second pulse signal is generated may be set short.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing positions of a Hall sensor and magnetic poles in the first embodiment.

FIG. 3 is a diagram showing an encoder in the first embodiment.

FIG. 4 is a timing chart showing a signal waveform in each part of FIG.

FIG. 5 is a characteristic diagram showing the relationship between motor rotation speed, torque, and efficiency when an excitation signal with a duty ratio of 1/3 is used.

FIG. 6 is a characteristic diagram showing the relationship between motor rotation speed, torque, and efficiency when excitation signals with duty ratios of 1/3 and 1/2 are switched and used.

FIG. 7 is a characteristic diagram showing the relationship between the motor rotation speed, torque, and efficiency when an excitation signal with a duty ratio of ⅓ is used with an advanced phase angle.

FIG. 8 is a characteristic diagram showing the relationship between the motor rotation speed, torque, and efficiency when the excitation signals with duty ratios of 1/3 and 1/2 are used by advancing and switching the phase angle.

FIG. 9 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 10 is a diagram showing a modified example of the encoder in the first and second embodiments.

[Explanation of symbols]

 2 Brushless motor 4 Encoder 6a-6c Hall sensor 8 Photodetector 10 Timing signal generator 12 Speed detector 14 Phase angle detector 16, 18 Counter 20 Speed comparator 21 Duty indicator 22 Duty signal generator 26U-26W Stator coil 30 Duty signal generator

Claims (13)

[Claims] 1. A first pulse generating means for generating a first pulse signal in response to a predetermined phase angle position of a rotor of a brushless motor, and a second pulse signal for each rotation of the rotor by a predetermined angle. Second pulse generating means for generating, means for detecting the rotation speed of the motor, means for obtaining a deviation between the speed setting value of the motor and the speed detection value of the motor, the first and second pulses And a means for generating an excitation signal to the motor based on a signal, wherein the excitation signal generation means increases the duty ratio or the lead angle of the excitation signal as the deviation becomes smaller. Phase angle controller for brushless motor. 2. The excitation signal generating means has a counter for counting each of the first and second pulse signals, and generates the excitation signal based on a count value of the counter. 1. Brushless motor controller. 3. The excitation signal generating means has a first counter for counting the first pulse signal and a second counter for counting the second pulse signal, and count values of the first and second counters. The controller for a brushless motor according to claim 1, wherein the excitation signal is generated based on the following. 4. The brushless motor control device according to claim 1, wherein a cycle of the first pulse signal is larger than a cycle of the second pulse signal. 5. The first pulse signal generating means has a hall sensor provided inside and around the stator of the motor, and the second pulse signal generating means rotates in synchronization with the rotor of the motor. The brushless motor control device according to claim 3, further comprising an encoder. 6. The brushless motor control device according to claim 3, wherein the first and second pulse signal generating means are composed of encoders that rotate in synchronization with the rotor of the motor. 7. The excitation signal generating means fixes the duty of the excitation signal when the deviation becomes a predetermined value or less,
The controller of the brushless motor according to claim 1, wherein the lead angle is increased as the deviation becomes smaller than the predetermined value. 8. The excitation signal generating means reduces the duty of the excitation signal as the deviation becomes smaller than the predetermined value when the deviation becomes smaller than a predetermined value, and the lead angle makes the deviation smaller than the predetermined value. The control device for the brushless motor according to claim 1, wherein the control device is increased in size. 9. A first pulse generating means for generating a first pulse signal in response to a predetermined phase angle position of a rotor of a brushless motor; and a second pulse signal for each rotation of the rotor by a predetermined angle. Second pulse generating means for generating, means for detecting the rotation speed of the motor, means for obtaining a deviation between the speed setting value of the motor and the speed detection value of the motor, the first and second pulses And a means for generating an excitation signal to the motor based on a signal, wherein the excitation signal generating means increases the duty ratio and the lead angle of the excitation signal as the deviation becomes smaller. Phase angle controller for brushless motor. 10. The excitation signal generating means includes counters for counting the first and second pulse signals, respectively.
11. The brushless motor control device according to claim 10, wherein the excitation signal is generated based on a count value of the counter. 11. The brushless motor according to claim 10, wherein the excitation signal generating means controls the duty and the lead angle of the excitation signal in an angle unit corresponding to the cycle of the first or second pulse signal. Phase angle control device. 12. A speed setting of the motor based on a first pulse signal synchronized with a predetermined phase angle position of a rotor of a brushless motor and a second pulse signal generated each time the rotor rotates by a predetermined angle. A phase angle control method for a brushless motor, characterized in that the phase of the excitation signal to the motor is controlled so that the duty ratio and the lead angle increase as the deviation between the value and the detected speed value of the motor decreases. 13. The phase angle control method for a brushless motor according to claim 12, wherein the duty and the lead angle of the excitation signal are controlled in an angle unit corresponding to the cycle of the first or second pulse signal.